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Note: GM does not provide timing chain timing marks, or information to perform timing chain service without the special tools shown in this procedure. Tools Required: – - J 36800 Camshaft Sprocket Timing Alignment Pin J 39579 Camshaft Sprocket Wrench Important: ^ ^ Before remove the timing chain, read the entire procedure. The timing chain on the engine is not to be replaced with the timing chain from any other model year. The timing sprockets are different on the engine and the shape of the links matches the sprockets. Engine damage may result if the wrong timing chain is used. The timing chain and the crankshaft sprocket must be marked in order to insure reassembly with the same side facing out at the time of reassembly. ^ Caution: Refer to Battery Disconnect Caution in Service Precautions. 1. Disconnect the negative battery cable. 2. Remove the engine front cover. Refer to Engine Front Cover Replacement. 3. Rotate the crankshaft clockwise (as viewed from the front of the engine, normal rotation) until the camshaft sprocket timing dowel pin holes line up with the holes in the timing chain housing. 4. The crankshaft sprocket keyway should point upwards and line up with the centerline of the cylinder bores. This is the Timed position. 5. Remove the timing chain guides. 6. Raise and support the vehicle. Refer to Vehicle Lifting. 7. Ensure that all of the slack in the timing chain is above the tensioner assembly. 8. Remove the timing chain tensioner. 9. The timing chain must be disengaged from any wear grooves in the tensioner shoe in order to remove the shoe. Slide a screwdriver blade under the timing chain while pulling the shoe outward. Notice: Do NOT attempt to pry the sprocket off the camshaft or damage to the sprocket or chain housing could occur. 10. If difficulty is encountered in removing the timing chain tensioner shoe, use the following procedure in order to remove the intake camshaft sprocket: 10.1. 10.2. 10.3. 10.4. Lower the vehicle. Hold the intake camshaft sprocket with the J 39579 and remove the sprocket bolt and washer. Remove the washer from the bolt and rethread the bolt back into the camshaft by hand (the bolt provides a surface to push against). Remove the intake camshaft sprocket. Use a three-jaw puller in the three relief holes in the sprocket.

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1. Remove the engine front cover; refer to the procedure in this section. 2. Remove the (A) crankshaft sensor ring from the (B)crankshaft (6303). 3. On WEP engines, use the (A) Camshaft Positioning Tool to position the (B) camshaft. 4. on REP engines, rotate the crankshaft until both camshaft keyways are 90° from the cam cover surface. On REP and WEP engines, make sure the copper links line up with the dots on the camshaft sprockets. 5. On REP equipped engines, install the (A) Cam Positioning Tool and the Camshaft Positioning Tool Adapters on the (B) camshaft. 6. On WEP engines, install the (A) Camshaft Holding Tool on the (B) camshaft. 7. Remove the (A) LH timing chain tensioner bolts and the (B) LH timing chain tensioner. 8. Remove the (A) RH timing chain tensioner bolts and the (B) RH timing chain tensioner. 9. Remove the LH and RH timing chain tensioner guides from the dowel pins. 10. CAUTION: At no time, when the timing chains are removed and the cylinder heads are installed may the crankshaft or camshaft be rotated. Severe piston and valve damage will occur. Remove the RH and LH timing chains and crankshaft sprockets. 1. Lift RH timing chain off of the camshaft sprocket and slide the timing chain and crankshaft sprocket off of the crankshaft. 2. Lift the LH timing chain off the camshaft sprocket and slide the timing chain and the crankshaft sprocket off of the crankshaft. 11. On REP engines, remove the chain guides. 1. Remove the LH timing chain guide bolts. 2. Remove the LH timing chain guide. 3. Remove the RH timing chain guide bolts. 4. Remove the RH timing chain guide.

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Checking Timing An access plug is provided in the cam drive belt cover so that camshaft timing can be checked without removal of the cover or any other parts. 1. Remove the access plug from the cam drive belt cover. 2. Rotate the crankshaft so that the No. 1 piston is rising on compression stroke. 3. Set the crankshaft to TDC by aligning the timing mark on the crank pulley with the TC mark on the belt cover. Always turn the engine in the direction of normal rotation (clockwise, as viewed from the front). Backward rotation may cause the timing belt to jump time, due to the arrangement of the belt tensioner. 4. Look through the access hole in the belt cover to make sure that the timing mark on the cam drive sprocket is lined up with the pointer on the inner belt cover. 5. Install the belt cover access plug. Adjusting Timing Belt SPECIAL SERVICE TOOL(S) REQUIRED Description Crankshaft Belt Tension Adjusting Tool T74P-6254-A 1. Remove the outer timing belt cover as outlined in this section. CAUTION: Attempting to adjust timing belt tension without loosening spring pivot bolt will break Crankshaft Belt Tension Adjusting Tool T74P-6254-A when relieving tension on the belt. 2. If belt timing or tension is incorrect, loosen timing belt spring pivot bolt. 3. Hold tensioner with Camshaft Belt Tension Adjusting Tool T74P-6254-A. 4. While holding tensioner, loosen adjusting bolt and gradually release spring tension. Loosening Timing Belt Tensioner, 2.3L Tool Number 8 — 5. Using adjusting tool, pry tensioner away from belt. While holding, tighten adjusting bolt. There should be no tension on belt. Camshaft Timing Belt, 2.3L I-4 Timing Mark on Camshaft Sprocket Remove the bolts holding the crankshaft position sensor in place and pull the sensor assembly free of the dowel pin. 7. Remove the crankshaft pulley , crankshaft pulley hub and timing belt guide. 8. Remove the drive belt and inspect it for wear or damage. If the belt is damaged, replace it. 9. Remove one spark plug from each cylinder. 10. If not done: a. Loosen tensioner adjusting bolt. b. Using Camshaft Belt Tension Adjusting Tool T74P-6254-A, pry tensioner clockwise against spring tension as far as possible. c. Tighten adjusting bolt to hold tensioner in released position. 11. Align crankshaft so number one piston is at TDC (top dead center) as indicated by timing mark. 12. Line up camshaft sprocket timing mark with inner timing belt cover timing mark and key is pointing down.